In recent years, quantitative amplification, such as qPCR, is a fast growing field. One specific development in this field is the so called digital PCR (dPCR) which is used for the detection of sequence variants with a very high sensitivity. Using dPCR, one mutation out of up to 105 individuals can be detected. Such sensitivity cannot be reached by any other quantitative amplification method.
Technical challenges using dPCR are mainly the generation of the aqueous droplets in a hydrophobic environment. The aqueous droplets are used as compartments in which at average one single nucleic acid molecule is amplified and detected. Thus a single sample is partitioned into thousands or millions of individual reaction chambers, each containing either one or no copies of the sequence of interest. By assessing the number of positive partitions in which the target sequence could be detected versus the number of negative partitions, an exact determination of the original number of copies of a DNA in the original sample is possible. The sensitivity, efficiency and resolution power of a digital PCR system depends mainly on the number of aqueous partitions which can be derived from a single aqueous sample and on the size distribution among individual aqueous droplets.